Double-current overload-relay.



R. J. PARSONS.

DOUBLE CURRENT OVERLOAD RELAY.

APPLlCATlON FILED AUG.9. 1915 1,273,659. Patented Ju1y23,191s.

Inventor:

Robert J. Pa ons, swgm UNITED STATES PATENT OFFICE.

ROBERT J. PARSONS, 0116 SCHENECTADY, NEW YOBK, ASSIGNOR 'IO GENERALELEGTRIG COMPANY, GOB EATI N NEW YQB 'DQUBLE-CURRENT OVERLOAD-RELAY.

Specification of Letters Patent.

Patented July 23, 1918.

Application filed August 9, 1915. Serial Ne le 146.

vices for electric circuits, whereby an eX- cessi've current will insure an opening of the circu t to prevent 1n ury to translating devices connected thereto.

circuit breaker adapted to operate at either of two different values of current. Theinvention is particularly useful for operation on a circuit in which the potential of the current difl'ers from time to time. A ram'iliar instance of this kind is an electric railway on which the cars operate at 600 volts on some parts of the line and at 1200 volts on other parts. In an equipment of this kind, the car is usually provided with four motors, which are all connected in parallel when running at full speed on a 600 volt section of the road. But when the car enters a 1200 volt section, itis customary, when the motors run at full speed, to connect them only in series-parallel 7 (two parallelgroups of two in series) in order that the voltage drop across each moto'r' maybe the same as on the 600 volt section. means that the resistance they offer to the flow of the current will be four times as great as when they are connected all four in parallel; but inasmuch as the voltage has been doubled, the current consumed will be one-half of that which is taken on the 600 volt section.

It is customary to protect the motors by an automatic circuit breaker, having its actuating coil in series with the motors. But a circuit breaker is usually set to openat an overload of afew amperes above maxi mum operation, so that if it is set to care properly for the normally high currenton the 600v volt section of the line, it will be entirely out ofadjustment for the lower current upon the 1200 volt section, and will fail to open upon what would be a dangerous overload for that section. V The object of my invention is to provide a circuit breaker 1; will aawmau an ma s.

I More specifically, my mventlo'n relates to an overload This arrangement of the motors date itself to the change from operation on one voltage to operation on another, with the corresponding change in current, and w ll protect the motors equally well under both conditions. i

in one embodiment, my invention comprlses acircuit breaker having a series tripping coil divided into two parts, one of which may have double the number of turns that the other has; Each part has its own armature, and both arm-atures' are arranged to trip the catch which controls thecircuitbreaking contacts. A shunt coil locks the armature of the larger part of the coil when the circuitcarriesthe lowerpotential and the larger current, so that the circuit cannot be opened until thepredeter'mined overload is reached, at which time the smaller part of the coil will be able to trip the catch.

xThe accompanying drawing is an elevationof the operativeparts of my improved circuit breaker. v

Thelseries tripping coil is composed of a heavy conductor whose terminalsare attached to blocks 1, 2 suitably secured to a panel 3 of insulating material. The coil is really made up of two coils in series, one coil 4 having a smaller number of turns than the other coil In the drawing the coil t'has one and a half turns and the coil 5 has three turns, the magnetic circuits not being shown. Each coil has a suitable core 6 and a tripping device comprising an armature pivoted in a position to be attracted by thesmaller coil. Armature 7 is pivoted at 8 to cooperate with the smaller coil and armature 9-is pivoted at 10 in position to coiiperate with the larger coil. An adjustable stop under each armature, such as the set screw 11, enables the air gaps between the armatures and their cores to be adjusted to calibrate the instrument for differing currents.

The tripping mechanism comprises a catch 12 pivoted to the panel at 13 and having two arms 14 and 15 adapted to be actuated respectively by the tails 16 on the armatures 7 and 9 to trip the catch 12. This catch has a shallow hook 17'which engages the end of one arm 18 of a bent lever, pivoted at 19. The other arm 20 of said lever is attached to the member 21 which carries one or more circuit breaking' contacts 22, These contacts may and as shown are intended to open the control circuit of the motors, that is they will cause the comm??? (1. 9?

'holds the circuit breaking contacts closed until an overload occurs.

The locking device comprises a shunt coil 2 which is secured to the panel and cooperates with an armature 25 pivoted at 26. A compression spring 27 having one end fixed at 27 and its other end abutting againstan arm 28 on said armature tends to hold the armature withdrawn from the coil. A stop finger 29 on said armature,

will be moved into the path of the armature 9 when saidshunt coil is energized and attracts its armature 25. The shunt coil is energized when the device is operating on the low potential section of the circuit; but is deenergized when the higher potential (but smaller current) is being used. This shunt coil is controlled by the operator preferably through the commutating switch (not shown) which must be operated to change the control circuits in going from one voltage to another.

The operation is as follows: So long as the car remains on the low voltage section, the shunt coil 24 is energized and its armature 25'swings the stop 29 into the path of the armature 9 and prevents it from tripping the catch 12. Under these conditions, it will require an overload above the maximum operating current of the 600 volt section,that is to say, above 400 amperes, for

instanceto enable the smaller coil 4: to lift its armature and trip the catch 12, thereby disengaging the hook 17 from the arm 18, thus releasing the levers 18, 20 and permitting the switches to open by gravity.

But when the car is operating on the 1200 volt section, the shunt coil 24 will not be energized and the armature 9 will be free to be lifted by the larger coil 5, which has twice the ampere turns of the smaller coil 4, and trip the catchfwhen the maximum operating current is exceeded.

It will be seen that my improved circuit breaker 'isthus capable of protectingthe car motors or other translating devices from an excessive current whether the operating current on the line is high or low, and that it accomplishes this result automatically when the operator SlllftStllB commutating switch in going from one voltage to the other. The

parts are few and simple, and do not easily get out of order.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means. i

lVhat l clainr as new and desire to secure by Letters Patent of the United States, is,

1. The combination in a circuit breaker adapted to open at either 'oftwo difierent values of current, of means for. tripping the breaker comprising two windings in series and two armatures therefor, one of which is actuated responsively to the lower and the other of which is actuated responsively to the higher value of current, and means for preventing the armature responsive to the lower value of current from operating to trip the breaker when the breaker is con-' 2. The combination in a circuit breaker adapted to open at either of two different values of current, of two windings in series and two armatures therefor, one of which is actuated responsively to the lower and the other of which is actuated resp'on sively to the hlgher value of current, a $1114 gle tripping mechanism actuated by either armature, and means for preventing the armature responsive to the lower value of current from operating the tripping mech anism when the breaker is connected to be opened' responsively to the higher value of current.

3. The combination in a circuit breaker adapted to open at either of two diiferent values of current, of means for tripping the breaker comprising two 'armatures, one of which is actuated responsively to the lower and the other'of which is actuated responsively to the higher value of'current, of an electromagnetically device for preventing operation of the armature responsive to the lower value of current when the breaker is connected to be opened responsively to the higher value of current.

'4. The combination in a circuit breaker adapted to operate at a high value of cur actuated locking higher value of current than the other, and

.circuit is connected to a source of supply or" high voltage, of a single tripping mechanism. for the circuit breaker set into operation by either of two armatures, one of which is actuated responsively to a higher value of current than the other, and electromagnetically controlled locking ieans brought into effective operation when the circuit to be protected is connected to the source of supply of low voltage to render the armature actuated responsively to the low value of current inoperative.

6. A circuit breaker having two tripping coils in series responsive respectively to dif terent current strengths, an armature for each coil, a single tripping mechanism actuated by either armature, and means for locking the armature responsive to the lesser current strength when the current strength is high.

7. A circuit breaker having two tripping coils in series, a tripping mechanism, an actuating device for said tripping mechanism associated with each coil so that each coil will operate to trip the tripping mechanism independently, one of said actuating devices responsive toa lesser value of cur rent than the other, and means for locking the actuating device responsive to the lesser value of current strength when the current strength is high.

S. A circuit breaker having two tripping coils in series and responsive respectively to difierent current strengths, a tripping mechanism, an actuating device for said tripping mechanism associated with each coil so that each coil will trip to operate the tripping mechanism independently, and means for locking the one of said actuating devices which is associated with the coil responsive to thelesser current strength when the current strength is high.

9. The combination in an overload circuit breaker adapted to be opened at either of two different values of current, of a switch member, electromagnetically controlled means for moving the switch member to closed position, means responsive to variations of current strength for causing the switch member to open at either of two difierent values of current, a shunt coil, and a locking device controlled by the shunt coil for preventing the switch member being opened responsively to the lower value of current when the breaker is to be opened responsively to the higher value of current.

10. The combination in an overload cir cuit breaker adapted to open at either of two different values of current, of a switch member, an electromagnet for moving the switch member to the closed position, a tripping mechanism having a catch for holding the switch member in the closed position, means responsive to variations of current strength for causing tripping mechanism to release the catch and permit the switch member to open at either of two different values of current, and an electromagnetically controlled locking device for preventing the tripping mechanism being operated responsively to the lower value of current when the breaker is to be opened responsively to the higher value of current.

11. The combination in an overload cir-- cuit breaker adapted to open at either of two different values of current, of a switch member, an electromagnet for moving the switch member to the closed position, a tripping mechanism having a catch for holding the switch member in the closed position, two series of coils, one of which has more turns than the other, an armature associated with each series coil and adapted to independently operate the tripping mechanism to release the catch and cause the switch to open, an electromagnetically controlled locking means for preventing the armature associated with the series coil having the greater number of turns from operating the tripping mechanism when the breaker is to be opened responsively to the higher value of current.

In witness whereof, I have hereunto set my hand this 4th day of August, 1915.

ROBERT J. PARSONS.

copies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents, Washington, D. G.

Correct ion in It is hereby certified that in Letters Patent N 0. 1,273,659, granted July 23, 1918, upon the application of Robert J. Parsons, of Schenectady, New York, for an improvement in Double-Current Overload-Relays, an error appears in the printed speoificetion requiring correction as follows: Page 3,lir 1e 93, claim 11, strike out the word 0f-, first occurrence; and that the said Letters Patent should be read with this correction therein that the same may conferrh to the record ofthe case in the Patent Ofiice. I I

Signed and sealed this 27th day of August, A. D., 1 918.

SEAL] F,=-W.-Il. CLAY,

' Acting Commissioner ofPatenta. Cl. l75-294. 

